Insightful rooks

August 9, 2009 • 11:40 am

by Greg Mayer

Matthew Cobb, my fellow guest blogger, has called my attention to a recent paper in Current Biology (abstract only) by Christopher Bird (yes, that’s his name) and Nathan Emery on the behavior of rooks (Corvus frugilegus) that was covered by the BBC and the Times. There’s also a video on the Current Biology website (both this and the BBC video are behaving badly, but the Times‘ is working for me).

A rook on Dartmoor, from Wikipedia
A rook on Dartmoor, from Wikipedia

What Bird and Emery have shown is that rooks will add stones to a tube of water, raising the water level, so they can reach the water to drink it. As many have noted, this corresponds quite closely to Aesop’s fable of the crow and the pitcher. This shows a remarkable cognitive ability, which seems actually insightful.  Crows and their relatives, especially ravens, have been the subject of much recent research showing that they have quite impressive intelligences.  The work of Bernd Heinrich (see, for example, his Mind of the Raven) is especially notable.

I should note here that unlike America, which has one common species of crow (Corvus brachyrhynchos; link is from a great site maintained by the Cornell Laboratory of Ornithology), Britain has several species of crows, including the rook, the jackdaw, and the chough (the latter not actually very common, but I like the sound of its name; links from another great site from the Royal Society for the Protection of Birds— h/t to Matthew). Several species also occur in Greece, so Aesop’s fable may have applied to rooks. Ravens are basically large-bodied crows; the common raven, Corvus corax, is found throughout much of the northern hemisphere.

16 thoughts on “Insightful rooks

  1. Would it be any different if the rocks were already in the cage instead of being offered to the bird (“hé, he is giving me some rocks, presumably i have to do something with them but what?; ah throw them in the tube, they fit nicely… the worm is rising i can eat it! jay”).
    Is this a case of manipulating the subject?

    1. Maybe, but the thought process you are describing seems about the same complexity as “Oh, the worm the worm, I need the worm! Now I have a use for those rocks that I keep stubbing my toes on.”

  2. I remember looking out my window and seeing some crows pick up the mothballs I had put in my flower bed. They held the mothballs in their beaks and rubbed them through their feathers, presumably for pest control. I was astounded but later read that I wasn’t the first to observe this. Apparently they, and other types of birds, also use ants as a pest control product, rubbing them on their feathers.

  3. There is more than one species of crow in North America. For example, the fish crow (Corvus ossifragus) is endemic to the southeastern United States. And of course we have many other corvids (ravens, jays, magpies).

    1. You beat me to it. Fish crows and common crows are about equally common where I live (Southern Maryland), and I’m not too far from raven in the Appalachians.

      1. I was certain that even as I was typing that someone whould beat me to the punch. And speaking of home territory corvids, I’m in Florida and I have had the rare treat of seeing our scrub jays (as well as the much more common western variety). They are lovely, charismatic birds.

    2. I was going to mention the fish crow (Corvus ossifragus) of the southeastern US, but didn’t want to get too far into the details of crow systematics and distribution. There are two other crows in the US as well, but both have very small ranges: the northwestern crow (Corvus caurinus; coastal Alaska, BC, Washington) and the Tamaulipan crow (Corvus imparatus; found in the US only in Brownsville, Texas). The fish crow is very similar to the common crow, and many people living within their joint range don’t realize there are two species. The chief way to tell them apart is the voice. Having grown up where both species occur, I was never sure I’d seen a fish crow until a visit to Annapolis, Maryland, where a flock of fish crows all calling made the vocal differences unmistakable.

      The other distinctive thing about British crows is that, unlike the common and fish crows in America, they’re all rather different morphologically– take a look at them at the RSPB website. They have not only species diversity, but what Steve Gould called ‘disparity’.


      1. I didn’t realise that they now consider the hooded crow and carrion crow to be separate species. They do interbreed a bit, and I’ve seen hybrids here in England occasionally.

        Corvids in general are very interesting to watch.

    1. The fact that the crows did not recognise the Cheney mask as a symbol of danger indicates that they are no more intelligent than half the US human population.

  4. Fish crows range up the Atlantic coastal plain all the way to New England; they are not just southeastern.

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